Elbow prosthesis

ABSTRACT

A method and apparatus for replacing a selected portion of the anatomy is described. In particular, a prosthesis can be provided to replace a portion of an articulating joint, such as an elbow. The apparatus can be modular for various reasons and each of the modular portions can include a different dimension to achieve a selected result. For example, the prosthesis can achieve a different size condylar replacement, a selected offset, a selected articulation, or combinations thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 10/333,140 filed on Jan. 15, 2003, which is a National Stage ofInternational Application No. PCT/US01/22338 (published as WO 02/05728),filed Jul. 17, 2001, which claims priority to U.S. ProvisionalApplication No. 60/219,103 filed Jul. 18, 2000. Each of thesedisclosures are incorporated herein by reference.

FIELD

The present teachings relate generally to prosthetic devices used inarthroplasty and more particularly to a modular elbow prosthesis.

BACKGROUND

The present teachings relate generally to prosthetic devices used inarthroplasty and more particularly to a modular elbow prosthesis.

Linked or constrained elbow prostheses are known which comprise simplehinge arrangements, one component of which is attached to the end of thehumerus and the other component of which is attached to the end of theulna. The humeral component includes a shaft, that is cemented into aprepared cavity in the end of the humerus, and the ulnar componentincludes a shaft, that is cemented to the end of the ulna. Thecomponents of the prosthesis are connected together by means of a hingepin so that the prosthesis allows a single degree of freedom of movementof the ulna relative to the humerus.

One example of a linked elbow prostheses is disclosed in U.S. Pat. No.6,027,534 to Wack et al. In several respects, the linked embodiment ofthe '534 patent is typical of the designs for linked elbow prostheses inthat it includes a humeral stem that terminates at a yoke at its distalend, a bearing component, a retaining pin and an ulna stem. The bearingcomponent includes an oversized hole that is aligned with thelongitudinal axis of the bearing and adapted to accept the retaining pinin a slip-fit condition. The distal end of the bearing component iscoupled to the ulna stem. Despite the relatively widespread use ofdesigns of this type, several drawbacks have been noted.

One significant drawback concerns the assembly of the elbow prosthesisafter the surgeon has cemented the humeral and ulna stems to theirrespective bones. In using such conventionally configured linked elbowprosthesis devices, it is frequently necessary for the surgeon to drilla fairly large hole through the humerus so that the retaining pin may beinserted to the yoke of the humeral stem and the humeral bearingcomponent. As a high degree of accuracy is typically required to ensureproper alignment between the hole in the humerus and the hole in theyoke of the humeral stem, a significant cost can be associated with thisstep in the installation of an elbow prosthesis due to the cost of thetooling used and the amount of time required to complete this step. Theother method for attaching the prosthetic device includes inserting thedevice in its linked condition or placing the remaining piece into theyoke prior to fully seating the humeral component into the bone. Thislater method is typically somewhat difficult, given the limited amountof joint space that is available and the time constraints associatedwith the use of a PMMA bone cement.

Unlinked, or unconstrained, elbow prostheses are known which are similarto linked elbow prostheses but do not have a specific component whichmechanically couples the humeral and ulnar stems together. Rather, theprosthetic device is held together by the patient's natural softtissues. One example of an unlinked elbow prostheses is also disclosedin U.S. Pat. No. 6,027,534 to Wack et al. In several respects, theunlinked embodiment of the '534 patent is similar to the linkedembodiment discussed above in that it includes a humeral stem thatterminates at a yoke at its distal end, a humeral bearing component, aretaining pin, an ulnar bearing component and a ulnar stem. The outersurface of the humeral bearing is contoured to match the contour of theulnar bearing component. Despite the relatively widespread use ofdesigns of this type, several drawbacks have been noted.

For instance, a retaining pin that is transverse to the longitudinalaxis of the patient is employed, thereby making its removal difficult ifa bearing need to be replaced.

SUMMARY

It is taught to provide a prosthetic joint kit which transmits loadthrough mating bearing components over a spherically shaped area so asto minimize stresses in the bearing components, more accurately mimicnormal joint motion and provide for ease of assembly and revision.

In various forms, the teachings provide a prosthetic joint kit having afirst bearing component and a second bearing component. The firstbearing component includes a pair of condyle portions, each of whichhaving a spherically shaped bearing portion. The second bearingcomponent includes a pair of spherical bearing portions which areconfigured to engage the spherically shaped bearing portions of thefirst bearing component.

It is also taught to provide a prosthetic joint kit having a high degreeof modularity to permit a surgeon to easily configure the prostheticjoint kit to a patient.

It is also taught to provide a prosthetic joint kit having a pluralityof modular and interchangeable joint components which permit a surgeonto easily configure the prosthetic joint kit to a patient. Modularity isachieved through a plurality of interchangeable components such as stemstructures, bearing components and bearing inserts.

According to various embodiments it is taught to provide a prostheticjoint kit having a plurality of interchangeable bearing inserts whichpermit a surgeon to tailor the degree of varus/valgus constraint in adesired manner.

According to various embodiments it is taught to provide a prostheticjoint kit having a plurality of interchangeable bearing inserts, each ofwhich having a pair of spherical depressions. Each of the sphericaldepressions has a first portion and a second portion, with the secondportion being formed in a manner that defines the degree of varus/valgusconstraint.

According to various embodiments it is taught to provide a prostheticjoint kit which effectively limits the amount by which the prostheticjoint will articulate.

According to various embodiments it is taught to provide a prostheticjoint kit having a cam structure which is coupled to a first stemstructure such that the first stem structure contacts a second stem whenthe first stem structure has been rotated to a predetermined positionrelative to the second stem structure.

According to various embodiments it is taught to provide a prostheticjoint kit which employs a spherically-shaped bearing surface to transmitload between stem structures yet does not require fasteners or otherhardware to link the stem structures together.

According to various embodiments it is taught to provide a prostheticjoint kit having a first stem structure with a retaining structure and afirst spherical bearing surface and a second stem structure with aretaining aperture and a second spherical bearing surface. The retainingaperture is configured to receive the retaining structure when the firststem structure is at a first orientation relative to the second stemstructure. Relative rotation of the first stem structure from the firstorientation causes retaining structure to engage a portion of theretaining aperture which precludes the withdrawal of the retainingstructure therefrom. The retaining aperture and retaining structure aresized so as not to transmit load therebetween, thereby ensuring thatload is transmitted between the spherical bearing surfaces of the firstand second stem structures.

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the present disclosure.

DRAWINGS

Additional advantages and features of the present teachings will becomeapparent from the subsequent description and the appended claims, takenin conjunction with the accompanying drawings, wherein:

FIG. 1 is an exploded perspective view of a linked prosthetic joint kitconstructed in accordance with the teachings of a first aspect of thepresent teachings;

FIG. 1A is an exploded perspective view of a linked prosthetic joint kitsimilar to that of FIG. 1 but constructed in accordance with a firstalternate embodiment of the first aspect of the present teachings;

FIG. 2 is a longitudinal cross-sectional view of the linked prostheticjoint kit of FIG. 1 implanted in the arm of a person;

FIG. 3 is a cross-sectional view taken along the line 3-3 of FIG. 2;

FIG. 4 is an exploded perspective view of an unlinked prosthetic jointkit constructed in accordance with the teachings of a first aspect ofthe present teachings;

FIG. 5 is a longitudinal cross-sectional view of the unlinked prostheticjoint kit of FIG. 4 implanted in the arm of a person;

FIG. 6 is an exploded plan view of a linked prosthetic joint kitconstructed in accordance with a second alternate embodiment of thefirst aspect of the present teachings;

FIG. 7 is an enlarged portion of the linked prosthetic joint kit of FIG.6;

FIG. 8 is an exploded plan view of a linked prosthetic joint kitconstructed in accordance with a third alternate embodiment of the firstaspect of the present teachings;

FIG. 9 is a exploded side elevation view of a portion of a joint kitconstructed in accordance with the teachings of a second aspect of thepresent teachings;

FIG. 10 is an exploded side elevation view of a portion of a joint kitconstructed in accordance with a first alternate embodiment of thesecond aspect of the present teachings;

FIG. 11 is an exploded side elevation view of a portion of a joint kitconstructed in accordance with a third alternate embodiment of thesecond aspect of the present teachings;

FIG. 12 is a longitudinal cross-sectional view of a portion of a jointkit constructed in accordance with a fourth alternate embodiment of thesecond aspect of the present teachings;

FIG. 13 is an exploded side elevation view of a portion of a joint kitconstructed in accordance with a fifth alternate embodiment of thesecond aspect of the present teachings;

FIG. 14 is a cross-sectional view taken along the line 14-14 of FIG. 13;

FIG. 15 is a cross-sectional view of a portion of a joint kitconstructed in accordance with a sixth alternate embodiment of thesecond aspect of the present teachings;

FIG. 16 is an exploded side elevation view of a portion of linkedprosthetic joint kit constructed in accordance with the teachings ofvarious embodiments of a third aspect of the present teachings;

FIG. 17 is a cross-sectional view taken along the line 17-17 of FIG. 16;

FIG. 18 is a cross-sectional view taken along the line 18-18 of FIG. 16;

FIG. 19A through 19D are side elevation views of bearing insertsconstructed with varying degrees of varus/valgus constraint;

FIG. 20 is an exploded side elevation view of a portion of a linkedprosthetic joint kit constructed in accordance with the teachings of afirst alternate embodiment of the third aspect of the present teachings;

FIG. 20B is an exploded side elevation view of a portion of a linkedprosthetic joint constructed in accordance with the teachings of secondalternate embodiment of the third aspect of the present teachings;

FIG. 20C is a side view of an alternately constructed pin for linkingthe stem structures of the second alternate embodiment of the thirdaspect of the present teachings;

FIG. 21 is a bottom plan view of a portion of the linked prostheticjoint kit of FIG. 20 illustrating the bearing insert in greater detail;

FIG. 22 is a side elevation view of a portion of the linked prostheticjoint kit of FIG. 20 illustrating the clip member in greater detail;

FIG. 23 is a longitudinal cross-sectional view of a linked prostheticjoint kit constructed in accordance with the teachings of a variousembodiment of a fourth aspect of the present teachings;

FIG. 24 is a top plan view of the linked prosthetic joint kit of FIG.23;

FIG. 25 is an exploded top plan view of a linked prosthetic joint kitconstructed in accordance with the teachings of a various embodiment ofa fifth aspect of the present teachings;

FIG. 26 is a longitudinal cross-sectional view of the linked prostheticjoint kit of FIG. 25;

FIG. 27 is a longitudinal cross-sectional view similar to that of FIG.2, but illustrating the stem with an integrally-formed flange forcompressing a bone graft;

FIG. 28 is a side view illustrating a stem with an integrally-formed,resilient flange for compressing a bone graft;

FIG. 29 is a longitudinal cross-sectional view similar to that of FIG.2, but illustrating the stem of FIG. 28;

FIG. 30 is a longitudinal cross-sectional view similar to that of FIG.29, but illustrating the resilient flange as being fixedly but removablycoupled to the stem;

FIG. 31 is a partially broken-away exploded perspective viewillustrating an alternative coupling means for coupling the modularflange to the stem;

FIG. 32 is a longitudinal cross-sectional view similar to that of FIG.2, but illustrating the alternative coupling means of FIG. 31;

FIG. 33 is a view similar to that of FIG. 31 but illustrating a secondalternative coupling means;

FIG. 34 is a view similar to that of FIG. 31 but illustrating a thirdalternative coupling means;

FIG. 35 is a longitudinal cross-sectional view similar to that of FIG.2, but illustrating the alternative coupling means of FIG. 34;

FIG. 36 is an exploded perspective view of a prosthesis according tovarious embodiments;

FIG. 37 is a detailed cross-sectional view of an assembled prosthesisaccording to various embodiments;

FIG. 38 is an exploded plan view of a prosthesis according to variousembodiments; and

FIG. 39 is a detailed environmental view of a prosthesis implanted in ananatomy according to various embodiments.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses. Itshould be understood that throughout the drawings, correspondingreference numerals indicate like or corresponding parts and features.

With reference to FIGS. 1, 2 and 3 of the drawings, a linked prostheticjoint device constructed in accordance with the teachings of a firstaspect is generally indicated by reference number 10. Although theparticular prosthesis illustrated and discussed relates to a prosthesisfor use in reconstructing an elbow, it will be understood that theteachings have applicability to other types of linked and unlinkedprosthetic devices. As such, the scope of the present teachings will notbe limited to applications involving elbow prosthesis but will extend toother prosthetic applications.

In the particular embodiment illustrated, linked prosthetic joint 10 isshown to include a first stem structure 12, a second stem structure 14,a first bearing component 16, a second bearing component 18, a modularflange 20 and a tissue fastener 22. First stem structure 12 includes aproximal portion 30 and a distal portion 32. Proximal portion 30includes a stem member 34 which is adapted to fit within the medullarycanal 36 of a humerus 38. Distal portion 32 includes a generallyU-shaped member 40 which is fixedly coupled to the distal end ofproximal portion 30. U-shaped portion 40 includes a pair of spaced-apartlegs or furcations 42. A threaded fastener aperture 44 extendsperpendicularly through each of the furcations 42.

Second stem structure 14 includes a distal portion 50 which is adaptedto fit within the medullary canal 52 of an ulna 54. Second stemstructure 14 also includes a proximal portion 56 which is coupled tosecond bearing component 18. In the particular embodiment illustrated,second bearing component 18 is fixedly coupled to second stem structure14. However, second bearing component 18 may also be releasably coupledto second stem structure 14 as shown in FIGS. 9 through 12.

First bearing component 16 includes a pair of condyle portions 60, a pinportion 62 and a pair of fasteners 64. Condyle portions 60 and pinportion 62 are formed from a suitable material, such as cobalt chromiumalloy. Each condyle portion 60 is shown to include a spherically-shapedbearing portion 66, slotted aperture 68, a pin aperture 70 and amounting aperture 72. The pair of spherically shaped bearing portions 66collectively form a first bearing surface. Pin aperture 70 is sized toreceive an end of pin portion 62 to permit pin portion 62 to slidinglyengage condyle portions 60. Pin 62 can also be fixedly coupled with oneof said condyle portion 60 and slidingly engage second of said condyleportion 60. Each of the slotted apertures 68 is sized to slidinglyengage one of the furcations 42.

Second bearing component 18 is shown to include a cage portion 80 whichis fixedly coupled to the proximal portion 56 of second stem structure14 and a bearing member 82 which is fixedly coupled to the cage portion80. Bearing member 82 includes a pair of spherical bearing portions 84which are configured to engage the spherically shaped bearing portions66 of the condyle portions 60. The pair of spherical bearing surfaces 84collectively form a second bearing surface that mates with the firstbearing surface. Bearing member 82 also includes a through hole 86 whichis adapted to receive pin portion 62, preferably without transmittingload therebetween (i.e., pin portion 62 preferably does not contact thesurfaces of through hole 86). In the particular embodiment illustrated,bearing member 82 is fabricated from polyethylene which has been moldedto cage portion 80. Alternatively, bearing member 82 may be fabricatedfrom any other appropriate material such as a stainless steel, ceramic,pyrolytic carbon, cobalt chrome (CoCr) etc.

To use linked prosthetic joint 10, first stem structure 12 is implantedin humerus 38 such that proximal portion 34 is located in the medullarycanal 36 of the humerus 38 as shown in FIG. 2. Second stem structure 14is similarly implanted in ulna 54 such that distal portion 50 is locatedin the medullary canal 52. Pin portion 62 is next inserted to the pinaperture 70 of one of the condyle portions 60 and the opposite end ofpin portion 62 is placed through hole 86 and into the pin aperture 70 ofthe other one of the condyle portions 60. Second bearing component 18 ispositioned adjacent the distal portion 32 of first stem structure 12,furcations 42 are aligned to their respective slotted aperture 68 andcondyle portions 60 are slidingly engaged to furcations 42. Fasteners 64are inserted through their respective mounting apertures 72 andthreadably engaged to their threaded fastener aperture 44. When fullyseated, each of the fasteners 72, extends through its respectivefurcation 42 to prevent condyle portion 60 from rotating relative to thefurcation 42. At this point, first and second bearing components 16 and18 hingedly couple first and second stem structures 12 and 14 togetherin a linked or constrained manner.

Construction of linked prosthetic joint 10 in this manner is highlyadvantageous in that it permits the surgeon to insert the first andsecond stem structures 12 and 14 prior to or after assembling linkedprosthetic joint 10, as well as permits linked prosthetic joint 10 to beassembled in a relatively small space as compared to most of the otherprosthetic joints that are known in the art. Furthermore, the sphericalconfiguration of first and second bearing surfaces 66 and 84 permits theload which is transmitted through linked prosthetic joint 10 to bespread out over a relatively large area, rather than concentrated at asingle point or over a line of contact to thereby improve the durabilityof linked prosthetic joint 10.

Modular flange 20 may be employed to increase the resistance of firststem structure 12 to rotation within medullary canal 36. In FIGS. 1 and2, modular flange 20 is shown to include an internally threaded fastener90, and a unitarily formed flange structure 92 having a mount member 94and a flange member 96. Mount member 94 includes a locating cylinder 94a which is fixedly coupled to flange member 96 at its base and anexternally threaded fastener 94 b which is coupled to an opposite sideof locating cylinder 94 a. A mounting hole 98, which is sized to receivefastener 94 b, extends through internally threaded fastener 90. A bore100 formed through the base 102 of U-shaped portion 40 has a firstportion 104 which is tapered at one end to engage the edges ofinternally threaded fastener 90 and second portion 106 which is counterbored at the other end to engage the locating cylinder 94 a of mountmember 94. Internally threaded fastener 90 is threadably engaged tofastener 94 b to fixedly but removably couple modular flange 20 to firststem structure 12.

Modular flange 20 may be employed to generate a clamping force whichclamps a portion 108 of the humerus 38 between the proximal portion 34of the first stem structure 12 and the flange member 96. Preferably, abone graft 110 is employed in conjunction with modular flange 20 suchthat the clamping force produced by modular flange 20 is alsotransmitted to bone graft 110 to promote the attachment of bone graft110 to humerus 38 and the subsequent growth of bone graft 110. Thoseskilled in the art will understand that alternatively, a flange (notshown) which is unitarily formed with first stem structure 12 may beincorporated into linked prosthetic joint 10 to thereby increase theresistance of first stem structure 12 to rotation within medullary canal36. However, a flange which is unitarily formed with first stemstructure 12 could not be employed to generate a clamping force whichclamps a portion 108 of the humerus 38 between the proximal portion 34of the first stem structure 12 and the flange.

Tissue fastener 22 is shown in FIGS. 1 and 2 to be a device forattaching soft tissue, such as tendons 130, to linked prosthetic joint10. In this regard, the specific configuration of tissue fastener isbeyond the scope of this disclosure. Examples of suitable tissuefasteners are discussed in U.S. Pat. Nos. 5,380,334, 5,584,835,5,725,541, 5,840,078 and 5,980,557 which are hereby incorporated byreference as if fully set forth herein.

In the particular embodiment illustrated, tissue fastener 22 is shown toinclude a tissue clamp 132 and a threaded fastener 134. Tissue clamp 132includes an annular base 136 and a pair of prongs 138. Prongs 138 areforced through the soft tissue (e.g. tendons 130). Threaded fastener 134is inserted through a hole in base 136 and threadably engaged to secondstem structure 14, to fixedly but releasably couple tissue fastener 22and the soft tissue to second stem structure 14. Those skilled in theart will understand that tissue fastener 22 may also be used inconjunction with first stem structure 12.

In FIG. 1A, a linked prosthetic joint device constructed in accordancewith the teachings of an alternate embodiment of the first aspect of thepresent teachings is generally indicated by reference numeral 10 a.Linked prosthetic joint 10 a is shown to include first stem structure12, second stem structure 14, first bearing component 16 a, secondbearing component 18 a, modular flange 20 and tissue fastener 22.

First bearing component 16 a is similar to first bearing component 16 inall respects except that it is unitarily formed. Accordingly, pinportion 62 a is not removable form condyle portions 60 a. Second bearingcomponent 18 a is similar to second bearing component 18 in all respectsexcept that an insertion aperture 150 extends form through hole 86 aoutwardly through bearing member 82 a and cage portion 80 a.Accordingly, insertion aperture 150 renders the area of second bearingsurface 84 a somewhat smaller than second bearing surface 84. Secondbearing surface 84 a is otherwise identical to second bearing surface84.

To use linked prosthetic joint device 10 a, first and second stemstructures 12 and 14 are initially inserted to the humerus and ulna andfirst bearing component 16 a is fastened to the first stem structure 12using techniques similar to that discussed above for prosthetic jointdevice 10. First bearing component 16 a is then positioned adjacentsecond bearing component 18 a such that pin portion 62 a is in insertionaperture 150. Pin portion 62 a is then forced toward through hole 86 a.The distal end 152 of insertion aperture 150 is smaller than pin portion62 a to permit bearing member 82 a to engage pin portion 62 a in a snapfit manner, so as to inhibit the unintentional withdrawal of pin portion62 a from through hole 86 a. As discussed above, through hole 86 a ispreferably larger in diameter than pin portion 62 a. At this point,first and second bearing components 16 a and 18 a hingedly couple firstand second stem structures 12 and 14 together in a linked manner.

In FIGS. 4 and 5, an unconstrained or unlinked prosthetic joint deviceconstructed according to a first aspect of the present teachings isgenerally indicated by reference number 10′. Unlinked prosthetic joint10′ is shown to include a first stem structure 12, a second stemstructure 14, a first bearing component 16′, a second bearing component18′, a modular flange 20 and a tissue fastener 22. Unlinked prostheticjoint 10′ is shown to be operatively associated with a humerus 38′ andan ulna 54′ (FIG. 5), but those skilled in the art will understand thatthe teachings of the present teachings have application to prostheticjoints for other applications and as such, the scope of the presentteachings will not be limited to elbow joints.

First bearing component 16′ is similar to first bearing component 16 inthat it includes a pair of condyle portions 60′ and a pin portion 62′.However, first bearing component 16′ is preferably unitarily formed withpin portion 62′ extending between the spherically-shaped bearingportions 66′ and fixedly coupling the spherically-shaped bearingportions 66′ thereto. Like first bearing component 16, each of thecondyle portions 60′ of first bearing component 16′ includes a slottedaperture 68 and a fastener aperture 72. Spherically shaped bearingportions 66′ collectively form a first bearing surface. Like firstbearing component 16, first bearing component 16′ may be made from anyappropriate bearing material, such as cobalt chromium alloy.

Second bearing component 18′ is similar to second bearing component 18in that it includes a cage portion 80′ which is fixedly coupled to theproximal portion 56 of second stem structure 14 and a bearing member 82′which is fixedly coupled to the cage portion 80′. For purposes ofclarity, bearing member 82′ has not been shown in cross section in FIG.5. Bearing member 82′ includes spherical bearing surfaces 84′ which areadapted to engage the spherically-shaped bearing portions 66′ of thecondyle portions 60′. The pair of bearing surfaces 84′ collectively forma second bearing surface that mates with the first bearing surface.Bearing member 82′ also includes a raised portion 160 which is adjacentthe spherical bearing surfaces 84′ and configured to clear pin portion62′, preferably without transmitting load therebetween (i.e., pinportion 62′ preferably does not contact the surfaces of raised portion160). In the particular embodiment illustrated, bearing member 82′ isfabricated from polyethylene which has been molded to cage portion 80.Alternatively, bearing member 82′ may be fabricated from any otherappropriate material such as a cobalt chromium alloy, ceramics, orstainless steel.

To use unlinked prosthetic joint 10′, first stem structure 12 isimplanted in humerus 38′ such that proximal portion 34 is located in themedullary canal 36′ as shown in FIG. 5. Second stem structure 14 issimilarly implanted in ulna 54′ such that distal portion 50 is locatedin the medullary canal 52′. First bearing component 16′ is nextpositioned adjacent the distal portion 32 of first stem structure 12 andfurcations 42 are engaged to slotted apertures 68. Fasteners 64 areinserted through their respective mounting apertures 72 and threadablyengaged to their threaded fastener aperture 44. When fully seated, eachof the fasteners 64, extends through its respective furcation 42 toprevent its associated condyle portion 60′ from rotating relative tothereto. The proximal end of the ulna 54′ is positioned adjacent thedistal end of the humerus 38′ such that the pin portion 62′ is proximatethe raised portion 160 and the spherically-shaped bearing portions 66′of the condyle portions 60′ engage the spherical bearing surface 84′. Atthis point, first and second bearing components 16′ and 18′ are coupledtogether in an unconstrained or unlinked manner (i.e., held in positionby the soft tissues of the elbow). Construction of unlinked prostheticjoint 10′ in this manner provides many of the same advantages asmentioned above for linked prosthetic joint 10, such as the ability offirst and second bearing surfaces 16′ and 18′ to spread out the loadthat is transmitted through unlinked prosthetic joint 10′ over arelatively large area, rather than concentrate the load at a singlepoint or over a line of contact to thereby improve the durability ofunlinked prosthetic joint 10′.

As a surgeon may not always know prior to beginning an operation whethera patient would be better served by a linked or an unlinked jointprosthesis and as it is also occasionally necessary to convert anunlinked joint prosthesis to a constrained joint prosthesis, or viceversa, after implementation and use for a period of time, it is highlydesirable that the joint prosthesis be modular so as to provide thesurgeon with a high degree of flexibility which may be achieved in arelatively simple and cost-effective manner.

In FIGS. 6 and 7, a linked prosthetic joint constructed in accordancewith a second aspect of the present teachings is generally indicated byreference numeral 10 b. Linked prosthetic joint 10 b is shown to includefirst stem structure 12, a third stem structure 180, first bearingcomponent 16, a third bearing component 182. Third stem structure 180 issimilar to second stem structure 14 in that it includes a distal portion184 which is adapted to fit within the medullary canal of an ulna. Theproximal portion 186 of third stem structure 180 is coupled to thirdbearing component 182.

Third bearing component 182 is similar to second bearing component 18 inthat it includes a cage portion 190 and a bearing member 192. Cageportion 190 is fixedly coupled to the proximal portion 186 of third stemstructure 180. Bearing member 192 is fixedly coupled to cage portion190. Bearing member 192 includes a pair of spherical bearing surfaces194 which are configured to engage the spherically-shaped bearingportions 66 of the condyle portions 60 and a through hole 196 which isconfigured to receive pin portion 62, preferably without transmittingload therebetween (i.e., pin portion 62 preferably does not contact thesurfaces of through hole 196). Bearing member 182 also includes alateral buttress 200. Lateral buttress 200 includes a supplementarybearing surface 201 which is configured for receiving a capitellum 202of the humerus 204. In the particular embodiment illustrated, thirdbearing component 182 is fixedly coupled to third stem structure 180 andas such, the combination of the second stem structure 14 and secondbearing component 18 is interchangeable with the combination of thethird stem structure 180 and the third bearing component 182. However,those skilled in the art will understand that second and third bearingcomponents 18 and 182 may also be releasably coupled to a stemstructure, thereby eliminating the need for a third stem structure 180which would otherwise be identical to second stem structure 14. Thoseskilled in the art will also understand that the lateral butress mayalternatively be coupled directly to the third stem structure 180, beingeither releasably attached thereto or integrally formed therewith.

In FIG. 8, another linked prosthetic joint constructed in accordancewith the teachings of a second aspect of the present teachings isgenerally indicated by reference numeral 10 c. Linked prosthetic joint10 c is shown to include first stem structure 12, second stem structure14, a fourth stem structure 220, second bearing component 18, a fourthbearing component 222 and a fifth bearing component 224. Fourth stemstructure 220 includes a distal end 226 which is adapted to fit withinthe medullary canal of a radius and a proximal end 228 which is fixedlycoupled to fourth bearing component 222. Fourth bearing component 222includes a fourth bearing surface 230.

Fifth bearing component 224 is similar to first bearing component 16 inthat it includes, for example, a pair of condyle portions 60 and a pinportion 62 which permits first and fifth bearing components 16 and 224to be interchangeable. However, fifth bearing component 224 alsoincludes a lateral extension 240 which is adapted to replace at least aportion of the capitellum of the humerus. Lateral extension 240 definesa fifth bearing surface 242 which is configured to mate with fourthbearing surface 230. Preferably, at least a portion of each of thefourth and fifth bearing surfaces 230 and 242 is spherically shaped topermit loads transmitted therebetween to be spread out over a relativelylarge area, rather than be concentrated at a single point or along aline of contact.

In FIG. 9, a portion of a modular prosthetic joint kit constructed inaccordance with the teachings of a second aspect of the presentteachings is generally indicated by reference numeral 10 d. Modularprosthetic joint kit 10 d is shown to include second stem structure 14d, second bearing component 18 d, second bearing component 18 e and afastener 250.

Second bearing components 18 d and 18 e are similar to second bearingcomponents 18 and 18′, respectively, but are shown to be separable fromsecond stem structure 14 d. Second bearing components 18 d and 18 e alsoinclude a keel member 252, a clip member 254 and a fastener aperture 256which are formed in cage portions 80 d and 80 e, respectively. Keelmember 252 extends circumferentially around at least a portion of theperimeter of each of the cage portions 80 d and 80 e between clip member254 and fastener aperture 256. Clip member 254 includes a first portion258 which extends generally perpendicularly outward from its associatedcage portion and a second portion 260 which is coupled to the distal endof first portion 258. Second portion 260 extends generally outwardly andaway from first portion 258. Fastener aperture 256 is located acrossfrom clip member 254 and is sized to receive fastener 250.

Second stem structure 14 d is similar to second stem structure 14 inthat it includes a distal end 50 which is adapted to fit within themedullary canal of an ulna. Second stem structure 14 d also includes aproximal portion 56 d having a keel slot 264, a hook structure 266 andan internally threaded fastener aperture 268. Keel slot 264 is a slotthat is sized to receive keel member 252 in a slip fit manner. Keel slot264 and keel member 252 cooperate to resist relative medial-lateralmotion of cage portion (e.g. 80 d) relative to second stem structure 14d. Hook member 266 is generally U-shaped and defines a clip aperture 270which is sized to receive clip member 254.

To use modular prosthetic joint kit 10 d, the distal end 50 of secondstem structure 14 d is inserted in the medullary canal of the ulna. Themodularity of the prosthetic joint kit 10 d permits the surgeon toassess the patient's elbow to determine if the patient would be betterserved by a linked or an unlinked joint prosthesis. Once a decision hasbeen made as to which type of joint prosthesis would better serve thepatient, the surgeon selects an appropriate one of the second bearingcomponents 18 d and 18 e, places its clip member 254 into the clipaperture 270, pivots the cage portion (i.e. 80 d) toward the proximalend 56 d of the second stem structure 14 d to engage the keel member 252into the keel slot 264, inserts the fastener 250 through the fasteneraperture 256 and threadably engages the fastener 250 to the internallythreaded fastener aperture 268 to fixedly but releasably couple thesecond stem structure 14 d with the selected one of the second bearingcomponents 18 d and 18 e.

Those skilled in the art will understand that second bearing components18 d and 18 e may be coupled to second stem structure 14 d in variousother manners as illustrated in FIGS. 10 through 15. In FIG. 10, secondbearing component 18 f is shown to include a generally L-shaped trayportion 280 which is fixedly coupled to cage portion 80 f. Tray portion280 includes a keel slot 282 and a fastener aperture 284. Keel slot 282is operable for receiving a keel member 286 formed into the proximal end56 f of second stem structure 14 f. Fastener aperture 284 is operablefor receiving a fastener 288 which may be threadably engaged to aninternally-threaded fastener aperture 290 in the proximal end 56 f ofsecond stem structure 14 f to thereby permit second bearing component 18f and second stem structure 14 f to be fixedly but releasably coupled.

When coupled together, keel slot 282 and keel member 286 cooperate toresist relative medial-lateral motion of cage portion 80 f relative tosecond stem structure 14 f. Additionally, tray portion 280 cooperateswith an L-shaped flange 292 to which it abuts to further resist relativerotation between second stem structure 14 f and cage portion 80 f.

In FIG. 11, second bearing components 18 g and 18 h are shown to includea stem member 300 which extends from their respective cage portions 80 gand 80 h. Stem member 300 is engageable with a stem aperture 302 formedinto the proximal end 56 g of second stem structure 14 g. As shown inFIG. 12, stem member 300′ may alternatively be incorporated into theproximal end 56 j of second stem structure 14 j and stem aperture 302′may be formed into cage portion 80 j of second bearing component 18 j.

To provide the surgeon with additional flexibility, second bearingcomponent 18 h is shown in FIG. 11 to be slightly longer than secondbearing component 18 g (i.e. the distances from the centerline ofbearing member 82 to the confronting surface 304 of their respectivecage portions 80 g and 80 h is shorter for second bearing component 18g). This variation between second bearing components 18 g and 18 hpermits the surgeon to adjust the length of prosthesis 10 g to take intoaccount the physical characteristics of the patient's arm.

Modularity may also be incorporated into first stem structure 12 k asshown in FIGS. 13 and 14. First stem structure 12 k is shown to includea stem member 320 and a yoke member 322. The proximal end 324 of stemmember 320 is adapted to fit within the medullary canal of a humerus andthe distal end 326 of stem member 320 terminates at a dovetail aperture328 having a pair of inwardly tapering walls 330 and a tapered retainingwedge 332. An internally threaded fastener aperture 334 extends throughretaining wedge 332. Yoke member 322 is shown to be similar to thedistal end 32 of first stem structure 12 as it includes furcations 42and threaded fastener apertures 44. Yoke member 322 also includes adovetail member 338 having a pair of outwardly tapering surfaces 340, awedge slot 342 and a through hole 344. Dovetail member 338 is configuredto mate with dovetail aperture 328 such that engagement of retainingwedge 332 to the upper surface 346 of wedge slot 342 forces taperedsurfaces 340 against a respective one of the inwardly tapering walls330. A fastener 350 is inserted through hole 344 and threadably engagedto internally threaded fastener aperture 334 to fixedly but releasablycouple yoke member 322 and stem member 320 together.

Referring back to FIG. 11, second bearing components 18 g and 18 h arealso shown to include a pair of tang members 360. Each of the tangmembers 360 extends outwardly from its respective cage portion (i.e., 80g) and in the particular embodiment illustrated, is generallyrectangularly shaped. Each of the tang members 360 is sized to engage atang recess 362 in the proximal end 56 g of the second stem structure 14g. Engagement of the tang members 360 into their respective tang recess362 inhibits relative rotation between the second stem structure 14 gand the second bearing components 18 g and 18 h.

In FIG. 15, second bearing component 18 m is shown to have a fasteneraperture 380 which is formed through a bearing member 82 m and cageportion 80 m. Second stem structure 14 m, which is a threaded fastener382 in this embodiment, is disposed through the fastener aperture 380 insecond bearing component 18 m and threadably engaged to the cancellousbone 384 of the ulna 54 m. Construction in this manner is advantageousin that it permits the extent of the trauma experienced by the patientto be minimized. To further this goal, the distal end 386 of cageportion 80 m is shown to be generally cylindrically shaped so as tominimize the amount of bone that must be removed to prepare the ulna 54m for the second bearing component 18 m.

In FIGS. 16 through 18, a portion of a modular prosthetic joint kitconstructed in accordance with the teachings of a third aspect of thepresent teachings is generally indicated by reference numeral 10 n.Modular prosthetic joint kit 10 n is shown to include a bearing insert400, a retaining ring 402 and a second stem structure 14 n having anintegrally attached cage portion 80 n. Cage portion 80 n is shown toinclude a bearing aperture 406 for receiving bearing insert 400. In theparticular embodiment illustrated, cage portion 80 n also includes acircumferentially extending first ring groove 408 formed along theperimeter of bearing aperture 406 and operable for receiving a firstportion of retaining ring 402.

Bearing insert 400 is generally cylindrically shaped, having a pair ofspherical depressions 420 which collectively form a bearing surface thatis configured to mate with the spherically-shaped bearing portions 66 ofthe first bearing component 16. Bearing insert 400 also includes athrough hole 422 which is adapted to receive pin portion 62, preferablywithout transmitting load therebetween. A circumferentially extendingsecond ring groove 424 is formed in the outer perimeter of bearinginsert 400, the second ring groove 424 being operable for receiving asecond portion of retaining ring 402. Construction in this manner isadvantageous in that the surgeon may select a bearing insert 400 from aplurality of bearing inserts 400 to adapt prosthetic joint 10 n to thepatient.

In the particular embodiment illustrated, bearing aperture 406 is shownto include a plurality of radially outwardly extending tab apertures 430and bearing insert 400 is shown to include a plurality of radiallyoutwardly extending tabs 432. If desired, a first one of the tabapertures 430 and a first one of the tabs 432 may be sized differentlythan the remaining tab apertures 430 and tabs 432, respectively, to keythe bearing insert 400 to a specific orientation relative to second stemstructure 14 n.

With specific reference to FIG. 18, each of the pair of sphericaldepressions 420 includes a first spherical portion 450 and a secondspherical portion 454. Each of the first spherical portions 450 areformed into bearing insert 400 along an axis 456 that is coincident withthe longitudinal centerline of the bearing insert 400. Each of the firstspherical portions 450 are formed by a spherical radius approximatelyequal in magnitude to the spherical radius which defines thespherically-shaped bearing portion 66 of each of the condyle portions 60of first bearing component 16. The distance between the spherical radiialong axis 456 is equal to a predetermined distance, d.

The centerpoint 456 of the spherical radius that defines one of thefirst spherical portions 450 is employed to generate the secondspherical portion 454 on the opposite face of the bearing surface. Asecond centerline 468 is constructed from centerpoint 460 toward theopposite face at a predetermined constraint angle 470, such as 3.5degrees. The spherical radius that defines the second spherical portion454 on the opposite face is generated from a second centerpoint 472which is positioned along the second centerline 468 at a distance d fromcenterpoint 460. Construction of bearing insert 400 in this mannerpermits first bearing component 16 to rotate about centerline 456, aswell as to pivot relative to bearing insert 400 about thespherically-shaped bearing portion 66 of each of the condyle portions60.

A transition zone 480 is formed between each of the first and secondspherical portions 450 and 454 wherein a radius is formed at theintersection of the radii which define the first and second sphericalportions 450 and 454 to “soften” the transition between the first andsecond spherical portions 450 and 454 to render the movement of thecondyle portions 60 over the first and second spherical portions 450 and454 more comfortable to the patient.

Those skilled in the art will understand that the degree of theconstraint may be defined by the constraint angle. Accordingly, modularprosthetic joint kit 10 n preferably includes a plurality of bearinginserts 400, each having a bearing surface with a second sphericalportion 454 that is defined by a different constraint angle. Thoseskilled in the art will also understand that the degree of theconstraint may be additionally or alternatively defined by a constraintcharacteristic, which is illustrated in FIGS. 19A through 19D.

In FIG. 19A, bearing insert 400 a has a first predetermined constraintcharacteristic orientation wherein the centerlines which define theradii which define first and second spherical portions 450 and 454 arecontained in a plane which is generally perpendicular to thelongitudinal axis of the ulna. Construction of bearing insert 400 a inthis manner provides a varying degree of axial constraint. In FIG. 19B,bearing insert 400 b has a second predetermined constraintcharacteristic wherein the centerlines which define the radii whichdefine first and second spherical portions 450 and 454 are contained ina plane which is at approximately 45° to the longitudinal axis of theulna. Construction of bearing insert 400 b in this manner provides avarying degree of a combination of axial and varus/valgus constraint. InFIG. 19C, bearing insert 400 c has a third predetermined constraintcharacteristic wherein the centerlines which define the radii whichdefine first and second spherical portions 450 and 454 are contained ina plane which is generally parallel the longitudinal axis of the ulna.Construction of bearing insert 400 c in this manner provides a varyingdegree of varus/valgus constraint. In FIG. 19D, bearing insert 400 d isconstructed in a manner that is generally similar to that of bearinginserts 400 a, 400 b and 400 c except that the constraint angle employedto construct bearing insert 400 d is rotated form point x1 to y1 asindicated in FIG. 19 d. As a result, there is no single line oforientation in which the constraint is limited. Construction of bearinginsert 400 d in this manner provides a varying degree of constraint inboth an axial direction and a varus/valgus direction.

In FIGS. 20 through 22, a portion of a modular prosthetic joint kitconstructed in accordance with the teachings of an alternate embodimentof the third aspect of the present teachings is generally indicated byreference numeral 10 p. Modular prosthetic joint kit 10 p is similar tomodular prosthetic joint kit 10 n in that it includes a bearing insert400 p and a second stem structure 14 p having a integrally attached cageportion 80 p.

Cage portion 80 p is shown to include a bearing aperture 406 p forreceiving bearing insert 400 p. In the particular embodimentillustrated, cage portion 80 p includes a plurality of tab apertures 430p, a plurality of tab slots 500 and a hook structure 502. Each of thetab apertures 430 p extends axially through cage portion 80 p andcircumferentially around a portion of bearing aperture 406 p. Each ofthe tab slots 500 intersects one of the tab apertures 430 p and extendscircumferentially around a portion of bearing aperture 406 p away fromits associated tab aperture 430 p. Hook structure 502 is adjacent one ofthe tab apertures 430 p and extends radially inwardly andcircumferentially around a portion of bearing aperture 406 p. A clipslot 510 is formed circumferentially through hook structure 502.

Bearing insert 400 p is generally similar to bearing insert 400 exceptfor the configuration of the plurality of tabs 432 p and theincorporation of a clip structure 520 into a bearing body 522. Each ofthe plurality of tabs 432 p is relatively thin and do not extend axiallyacross bearing insert 400 p. This permits the tabs 432 p of bearinginsert 400 p to be aligned to a tab aperture 430 p and bearing insert400 p to be rotated so that each of the tabs 432 p is disposed withinone of the tab slots 500 to thereby prevent bearing insert 400 p frommoving in an axial direction.

Clip structure 520 is preferably a metal or plastic fabrication which issuitable for molding into bearing body 522. Clip structure 520 includesan arm structure 530 which extends from a clip body 532 and terminatesat its distal end at a hook member 534. Clip structure 520 is configuredand incorporated into bearing body 522 such when bearing insert 400 p isrotated to engage tabs 432 p into tab slots 500, arm structure 530simultaneously engages clip slot 510 in hook structure 502. Rotation ofbearing insert 400 p to a predetermined rotational position relative tohook structure 502 permits hook member 534 to engage an edge 540 of hookstructure 502. Arm structure 530 resiliently biases hook member 534against edge 540, thereby inhibiting rotation of bearing insert 400 pwhich would cause tabs 432 p to disengage tab slots 500.

In FIG. 20B, bearing insert 400 p′ is illustrated to be configuredsimilarly to bearing insert 400 p except that a locking aperture 800 isformed into one of the tabs 432 p′. Bearing insert 400 p′ is insertedinto bearing aperture 406 p′ aligned such that each of the tabs 432 p′is aligned to an associated one of the tab apertures 430 p′. Bearinginsert 400 p′ is then rotated so that each of the tabs 500′ is disposedwithin one of the tab slots 440 p′ and locking aperture 800 is alignedto a corresponding locking aperture 802 formed in the integrallyattached cage portion 80 p′ of second stem structure 14 p′. Engagementof tabs 500′ into their respective tab slots 440 p′ prevents bearinginsert 400 p′ from moving in an axial direction. Alignment of lockingapertures 800 and 802 to one another permits a pin 806 to be insertedtherethrough to prevent bearing insert 400 p′ from rotating relative tointegrally attached cage portion 80 p′. In the particular embodimentillustrated, pin 806 includes a head portion 808, a body portion 810 andan end portion 812. Head portion 808 has a diameter which is larger thanthe diameter of the hole formed by locking apertures 800 and 802. Bodyportion 810 is preferably smaller in diameter than the diameter of thehole formed by locking apertures 800 and 802.

A plurality of slots 814 are formed in end portion 812 which creates aplurality of fingers 816 which are flexible relative to the longitudinalaxis of pin 806. Fingers 816 flex inwardly toward the longitudinal axisof pin 806 when pin 806 is inserted to locking apertures 800 and 802,eliminating the interference therebetween to permit the fingers 816 ofend portion 812 to pass through integrally attached cage portion 80 p′and bearing insert 400 p′. Once the fingers 816 have passed throughintegrally attached cage portion 80 p′ and bearing insert 400 p′, theyflex outwardly away from the longitudinal axis of pin 806 to inhibit theunintended withdrawal of pin 806 from locking apertures 800 and 802.Intended withdrawal of pin 806 from locking apertures 800 and 802 may beeffected through the flexing of fingers 816 inwardly toward thelongitudinal axis of pin 806.

Those skilled in the art will understand, however, that the pin 806 forlinking first and second stem structures 12 and 14 p′ may be constructeddifferently. As shown in FIG. 20C, for example, the pin 806′ includeshead and end portions 808′ and 812′ having chamfered abutting surfaces808 p′ and 812 p′, respectively. The chamfered abutting surfaces 808 p′and 812 p′ can abut the locking apertures 800 and 802, similar to thepin 806. As illustrated, the pin 806 in FIG. 20B includes the headportion 808 that is larger than the locking apertures 800 and 802 andthe end portion 812 that can flex so that it can be smaller than thelocking apertures 800 and 802 to allow passage of at least a portion ofthe pin 806 through the locking apertures 800, 802. One skilled in theart will understand that a locking pin can generally pass through anaperture and be held therein, through some mechanism, to allow forinterconnection or locking of the various portions relative to oneanother. Nevertheless, the chamfered abutting surfaces 800 p′ and 812 p′can allow for a selected engagement of a pin 806′ between the lockingapertures 800, 802. Additionally, the end portion 812′ includes achamfered lead portion 812 p″. The chamfered lead portion 812 p″ canassist in allowing the pin 806′ to be passed through the lockingapertures 800, 802. Although it will be understood that the end portion808′ can be larger than the locking apertures 800, 802 so that the pincan only pass a selected distance through the locking apertures and beheld relative to the cage portion 80 p′ and the bearing insert 400 p′.As discussed above, in relation to the locking pin 806, the leading end812 can be allowed to pass through the locking apertures 800, 802,allowing the legs 816 to flex such that the head 812 passes through thelocking apertures 800, 802, similar to the head portion 812′ which isconfigured with the chamfered lead portion 812 p″ to allow for the pin806 to pass through the locking aperture 800, 802. However, the endportion 808′ is sized to not pass through the locking aperture 800, 802so that the pin 806′ can be held in a selected location. Pin 806′ isinstalled by simply pressing it through the bearing insert 400 p′.

In FIGS. 23 and 24, a portion of a modular prosthetic joint kitconstructed in accordance with the teachings of a fourth aspect of thepresent teachings is generally indicated by reference numeral 10 q.Prosthetic joint kit 10 q is shown to include first stem structure 12,second stem structure 14, first bearing component 16 and second bearingcomponent 18 q. Second bearing component 18 q is substantially similarto second bearing component 18 except that cage portion 80 q is shown toinclude a cam structure 600. Cam structure 600 includes a lobe member602 that extends radially outwardly and terminates at a tip 604. Lobemember 602 is configured such that tip 604 contacts the base 102 ofU-shaped member 40 to inhibit further relative rotation between firstand second stem structures 12 and 14 when the first and second stemstructures 12 and 14 are placed in a position corresponding to themaximum extension of a patient's arm. Configuration of second bearingcomponent 18 q in this manner is advantageous in that it limits theamount by which a patient may rotate their ulna relative to theirhumerus to prevent hyperextension of the joint.

In FIGS. 25 and 26, a portion of a modular prosthetic joint kitconstructed in accordance with the teachings of a fifth aspect of thepresent teachings is generally indicated by reference numeral 700.Prosthetic joint kit 700 is shown to include a first stem structure 702and a second stem structure 704. First stem structure 702 includes astem member 710, the distal end of which is configured to fit within themedullary canal of an ulna. A first bearing 712 and a coupling structure714 are incorporated into the proximal end of first stem structure 702.First bearing structure 712 is generally spherically shaped. Couplingstructure 714 includes a link member 720 and a retainer member 722. Linkmember 720 is fixedly coupled to first bearing 712 at a first end and toretaining structure 722 at a second end with link member 720 extendingtherebetween along an axis generally coincident the longitudinal axis offirst stem structure 702. Retaining structure 722 is illustrated to bespherically shaped with flattened ends.

Second stem structure 704 is shown to include a stem member 730 with aproximal end that is configured to fit within the medullary canal of ahumerus. A second bearing structure 732 is incorporated into the distalend of second stem structure 704. Second bearing structure 732 includesa generally spherical second bearing surface 740 and a T-shaped couplingaperture 742. A first portion 744 of coupling aperture 742 has a widthwhich is larger than the width of retaining structure 722. First portion744 is oriented at a position of maximum flexion. In the particularembodiment illustrated, the position of maximum flexion is illustratedto be about 90° to the longitudinal axis of second stem structure 704.However, those skilled in the art will understand that the position ofmaximum flexion may be tailored in a desired manner and may range ashigh to an angle of approximately 135° to 150° to the longitudinal axisof second stem structure 704, depending on the particular application. Asecond portion 746 of coupling aperture 742 has a width which isslightly larger than that of link member 720. Second portion 746 extendscircumferentially around a portion of second bearing surface 740 in aplane that coincides with the longitudinal axis of second stem structure704. The first and second portions 744 and 746 of coupling aperture 742intersect and terminate at spherically shaped cavity 750.

To use prosthetic joint kit 700, first and second stem structures 702and 704 are inserted into the medullary canals of the ulna and humerus,respectively. First stem structure 702 is then positioned proximate thefirst portion 744 of coupling aperture 742 and retaining structure 722is inserted through first portion 744 and into spherically shaped cavity750. At this point, first and second bearing surfaces 712 and 740 are incontact with one another and transmit load therebetween rather thanthrough coupling structure 714. Coupling of first and second stemstructures 702 and 704 is complete when first stem structure 702 isrotated into second portion 746. In this position, first and second stemstructures 702 and 704 are linked or constrained since the width ofretaining portion 722 is larger than the width of second portion 746 andthereby prevents the withdrawal of first stem structure 702 fromcoupling aperture 742.

While the prosthetic joint devices 10 and 10 a have been illustrated ashaving modular flanges 20 that are fixedly but removably coupled to thefirst stem structure 12, those skilled in the art will understand thatthe teachings, in its broader aspects, may be constructed somewhatdifferently. For example, the stem structure and modular flange may beunitarily formed as shown in FIG. 27. In this embodiment, the stem 12 pis illustrated to be similar to the stem 12, but includes a flangestructure 92 p having a flange member 96 p and a coupling portion 96 p′that couples the flange member 96 p to the distal portion 32 p of thestem 12 p. The flange member 96 p is generally parallel the stem member30 p and is employed to compress a bone graft against the stem member 30p. Unlike the modular flange 20 that was described in detail, above, theflange structure 92 p must be fitted over a bone graft 110 or the bonegraft must be placed into the aperture 800 between the stem member 30 p.

Another example of an integrally formed (i.e., non-removable) flangestructure is illustrated in FIGS. 28 and 29. In this example, the stem12 q is illustrated to be similar to the stem 12 p in that it includes aflange structure 92 q having a flange member 96 q and a coupling portion96 q′ that couples the flange member 96 q to the distal portion 32 q ofthe stem 12 q. The flange member 96 q, however, is arcuately shaped andincludes a contact tab 804. The flange structure 92 q is formed with apredetermined degree of resiliency, which may result from thecharacteristics of the material from which the flange structure 92 q isformed or by controlling the geometry (i.e., cross-sectional shape andarea) of the flange structure 92 q. The resiliency of the flangestructure 92 q permits the flange member 96 q to act as a leaf springthat biases the contact tab 804 toward the stem member 30 q.Accordingly, the flange may be employed to apply compression to the bonegraft 110 q without fasteners or other securing means. As illustrated inFIG. 30, those skilled in the art will readily understand, however, thata predetermined amount of resiliency may also be incorporated into aflange structure 92 r that is fixedly but removably coupled to the stem12 r.

Those skilled in the art will also understand that although the modularflange 20 has been illustrated as being coupled to the stem 12 r via athreaded fastener 94 b, the teachings, in its broader aspects, may beconstructed somewhat differently. For example, cables 810 are employedto fixedly but removably retain the flange structure 92 s to the stem 12s as illustrated in FIGS. 31 and 32. The stem 12 s is generally similarto the stem 12, but includes a first coupling feature 812 instead of thebore 100. The flange structure 92 s includes a flange member 96 s and acoupling portion 96 s′. The coupling portion 96 s' includes a secondcoupling feature 814 that is configured to cooperate with the firstcoupling feature 812 to locate the flange member 96 s relative to thedistal portion 32 s of the stem 12 s. In the example illustrated, thefirst coupling feature 812 is a generally trapezoidal dovetail member816 that extends outwardly from the distal portion 32 s of the stem 12 sand the second coupling feature 814 is a dovetail aperture 818 that isformed into the coupling portion 96 s' and sized to engage the dovetailmember 816 in with a line-to-line fit (i.e., with very little or noclearance). The dovetail member 816 is preferably integrally formed ontothe stem 12 s but may alternatively be an independently formed componentthat is fixedly coupled to the distal portion 32 s via an appropriatecoupling means, such as threaded fasteners, press-fitting or shrinkfitting.

The flange member 96 s is shown to include a plurality of cross-holes820 that extend completely through the flange member 96 s in a directionthat is generally perpendicular the longitudinal axis of the flangemember 96 s. The cross-holes 820 are sized to receive the cable 810. Asthose skilled in the art will understand, the cables 810 are firstsecured around the humerus 38 s and the ends of the cables 810 areloosely secured via an appropriate coupling device, such as a cablesleeve 822. The cables 810 are then tensioned to urge the flange member96 s against the humerus 38 s and compress the bone graft 110 s by apredetermined amount. Thereafter, the coupling device is employed to fixthe ends of the cables relative to one another so as to maintain tensionin the cables 810.

While the first and second coupling features 812 and 814 have beenillustrated as being a dovetail member 816 and a dovetail aperture 818,respectively, those skilled in the art will appreciate that the firstand second coupling features 812 and 814 can be constructed somewhatdifferently. As illustrated in FIG. 33, for example, the first couplingfeature 812 t is illustrated as being a pair of pins 830 that arefixedly coupled to the distal portion 32 t of the stem 12 t and thesecond coupling feature 814 t is illustrated to be a corresponding pairof holes 832 that are formed into the coupling portion 96 t. The pins830 are preferably press-fit or shrunk fit into corresponding holes (notspecifically shown) that are formed into the distal portion 32 t of thestem 12 t but may be secured via other fastening means, such as welding,bonding, or threaded engagement where the pins 830 have a threadedportion that is threadably engaged to the holes in the distal portion 32t. Alternatively, the pins 830 may also be integrally formed as a partof the stem 12 t.

Another example is illustrated in FIGS. 34 and 35, where the firstcoupling feature 812 u is shown to include a mounting structure 840 withan arcuate mounting aperture 842 and the second coupling feature 814 uis shown to include an attachment hook 846. The mounting structure 840is coupled to the distal portion 32 u of the stem 12 u and extendsgenerally perpendicularly outwardly from the base 102 u of the U-shapedportion 40 u. The mounting aperture 842 is generally J-shaped andincludes a first portion 850, which is aligned generally perpendicularto the base 102 u, and an arcuate second portion 852, which extends awayfrom the stem member 34 u and the base 102 u. The attachment hook 846 isalso generally J-shaped, being configured to matingly engage themounting aperture 842. In this regard, the attachment hook 846 includesa leg portion 856 that extends downwardly from the flange member 96 uand an arcuate base member 858.

In coupling the first and second coupling features 812 u and 814 u,flange structure 92 u is initially positioned relative to the stem 12 usuch that the base member 858 is disposed within the first portion 850of the mounting aperture 842. The flange structure 92 u is then rotateddownwardly toward the stem member 34 u to permit the base member 858 toengage the second portion 852 of the mounting aperture 842. The cables810 are thereafter employed to fix the flange structure 92 u relative tothe stem 12 u.

With initial reference to FIG. 1 and further reference to FIG. 36, amodular joint prosthesis 1000 is illustrated. It will be understood thatthe illustrated modular prosthesis 1000 illustrated in FIG. 36 can besimilar to the prosthesis 10 illustrated in FIG. 1, though differencescan be provided and discussed herein. Nevertheless, like features andportions will be indicated with like reference numerals and notdescribed again in detail. Briefly, however, as discussed above, themodular prosthesis 1000 can be used as a linked elbow prosthesis,although it will be understood according to various embodiments that anunlinked or free elbow prosthesis can be provided, as discussed herein.The prosthesis 1000 can generally include the first stem structure 12,the second stem structure 14, a first bearing component 1002, the secondbearing component 18, and various other portions that can be provided orincluded in the modular prosthesis 1000 if selected. It will beunderstood that all or various portions are discussed above as includedin various embodiments. However, not each of the portions arenecessarily provided for each of the embodiments if so selected.

The first bearing component 1002 can define a first condyle portion 1004and a second condyle portion 1006. The condyle portions 1004, 1006, canbe similar to the condyle portions 60 illustrated and described above.According to various embodiments, each of the condyle portions 60 caninclude substantially similar spherical radii. Although the condyleportion 60 need not define a complete sphere, a portion of the sphere,which they can define, can include or define a spherical radius.According to various embodiments, however, the first condylar portion1004 can have a first spherical radius 1008 while the second condylarportion 1006 can include a second spherical radius 1010. The firstspherical radius 1008 can be different than the second spherical radius1010.

The spherical radii can be any appropriate dimension such as 1 mm toabout 3 cm, such as about 0.6 cm to about 2.0 cm. It will be understood,however, that the spherical radii 1008, 1010, can be any appropriatedimension. For example, the spherical radii 1008, 1010 can be selectedfor various purposes, such as to substantially mimic a specific anatomy,and as such the various ranges described herein are merely exemplary.Further, it will be understood that the dimensions 1008, 1010, which caninclude spherical radii, can be any appropriate dimensions. For example,it will be understood that the condylar portions 1004, 1006 need notspecifically define a portion of the sphere, a portion of a cylinder, orthe like. The condylar portions 1004, 1006 can be irregular such thatthey are not a regular shape or surface. The design of the condylarportions 1004, 1006 can be specific to various individuals andanatomies, thus not requiring a regular shape.

The condylar portions 1004, 1006 can include the various portions asdiscussed above. For example, the condylar portions 1004, 1006 candefine the bearing portion 66 which can be regular or irregular, asdiscussed above. Further, each can define the slotted apertures 68 orother appropriate connection portions, to interconnect with the distalportion 32, such as the legs 42 of the first end portion 12. It will beunderstood that the U-shaped portion 40, which includes the spaced apartthe legs 42, can also be referred to as a yoke or other appropriateportion. Further, each of the condyle portions 1004, 1006 can define thepin aperture 70 to interconnect with the condylar pin portion 62 tointerconnect the condylar portions 1004, 1006 in a selected manner. Asdiscussed above, however, the condylar portions 1004, 1006, can besubstantially formed as a single member or portion that can include thecondylar pin 62 a as a single portion with the condylar portions 1004,1006.

Further, as discussed above, the condylar portions 1004, 1006, thecondylar pins 62, and any other portions of the prosthesis 1000 can beformed of various materials. For example, it can be selected to form thecondylar portions 1004, 1006 from a single material, a compositematerial, or the like. For example, the condylar portions 1004, 1006 candefine the bearing surfaces 66 formed of a polymer material, such as ahigh molecular weight polyethylene. The second bearing member 18 canalso be made of similar materials. Nevertheless, they can also be formedwith a metal, metal alloy, ceramic, or the like to achieve variousresults.

Further, it will be understood that the second bearing portion 18 caninclude various features and be formed of various materials, includingthose discussed above. The second bearing member 18 can include thebearing cage 80, the second bearing cage 80 a which defines the slot150, or the substantially unconstrained or unlinked various embodimentsthat include the bearing member 82′ and the features thereof asdiscussed above. Therefore, it will be understood that the condylarportions 1004, 1006 can be interconnected with any appropriate secondbearing portion 18, 18′ including those described above.

Further, the prosthesis assembly 1000 can include various portions thatallow for the substantial non-linear alignment of the condylar portions1004, 1006 relative to one another. It can be selected to non-align oroffset a first center 1012 of the first condylar portion 1004 and asecond center 1014 of the second condylar portion 1006. It will beunderstood that the centers 1012, 1014, can be any operative center orportion of the prosthesis according to various embodiments and defininga geometrical center is merely exemplary. The centers can be offset invarious manners such as an anterior-posterior non-alignment, asuperior-inferior non-alignment, or combinations thereof.

For example, an anterior-posterior spacer kit can include a first spacer1016, a second spacer 1018, and a third spacer 1020. Each of the spacers1016-1020 can include a dimension 1016′-1020′ respectively. Thedimensions 1016′-1020′ can move or displace the selected condylarportions 1004, 1006 relative to the other. A selected spacer, such asthe spacer 1016, can be positioned in the slot 68 such that a passage1022 through the spacer 1016 aligns with the passage 72 through thecondylar portion 1006 so that when the leg 42 is positioned within theslot 68, the leg 42 is unaligned with the first condylar portion 1004. Asubstantially aligned axis 1024 can pass through the two centers 1012,1014 of the respective condylar portions 1004, 1006 and through thecondylar pin 62. Nevertheless, the spacer 1016 can offset a selectedcondylar portion, such as the second condylar portion 1006 relative tothe first condylar portion 1004. Therefore, an offset angle 1026 can beformed between the first condylar portion 1004 and the second condylarportion 1006.

In various configurations, such as an unaligned configuration, variousportions are optional. For example, the pin 62 is optional in variousconfigurations. As discussed above, the bearing members 1002 and 1006bear the force and the pin can assist with strength and stability of theassembly. Thus is the pin 62 can be omitted between the condyles.

The offset angle or distance 1026 can be any appropriate dimension. Theappropriate dimension can be selected for various purposes, such as thespecific anatomy of the patient, a selected result, or the like. Forexample, the offset angle can be about 1° to about 20°, such as about 3°to about 10°. Nevertheless, the offset angle can be any appropriateangle depending upon a selected condition. The offset angle 1026 can bealtered by choosing a different one of the spacers 1016-1020 and can beselected pre-operatively, intra-operatively, or at any appropriate time.

Each of the spacers 1016-1020 can include a passage or opening 1016a-1020 a. The opening can be a round bore, elongated, a slot or anyappropriate opening. The openings 1016 a-1020 a can be provided to alignor be oriented with the openings 72 in the first and second bearingmembers 1002 or 1006 and a selected passage 1016 a-1020 a.

The openings 72 can also be circular, oblong, slotted, or formed in anyappropriate shape or manner. The interaction of the opening 72 in thebearing members 1002 and 1006 and with the openings 1016 a-1020 a in thespacers 1016-1020 can help ensure an appropriate fit of the prosthesis1000.

A second set of spacers 1030-1034 can also be provided. The spacers1030-1034 can each include a dimension 1030′-1034′ respectively. Therespective dimension 1030′-1032′ can be any appropriate dimension andallow for a selected superior inferior offset. A selected spacer, suchas the spacer 1030, can be positioned in the slot 68 to offset thesecond condylar portion 1006 relative to the first condylar portion1004. The offset amount can be similar to the angle 1026 except in adifferent dimension or orientation. The spaces 1030-1034 can alsoinclude passages 1030 a-1034 a, respectively, that can be similar to thepassages 1016 a-1020 a. The passages 1030 a-1034 a can be round,slotted, oblong, etc. They can be provided to allow for a selectedorientation of the prosthesis 1000.

It will be understood, however, that any appropriate number of thevarious spacers such as the spacers 1016-1020 and the spacers 1030-1034can be provided for any appropriate purpose. For example, a plurality ofthe spacers 1016-1020 and 1030-1034 can be provided in minute anddiscreet differences to allow for an intra-operative selection of aselected offset or to allow for a plurality of offsets for creation froma set of instruments and portions.

With continuing reference to FIG. 36, a third set of spacers 1017, 1019,1021 can be provided. Although the discussion herein includes adiscussion related to three sets of spacers, it will be understood thata set of spacers can include any of the appropriate spacers, all of thespacers, or a selected portion thereof depending upon selected purposes.Nevertheless, the third set of spacers, called that for simplicity ofthe present discussion, can be formed dissimilar to the second set ofspacers 1030-1034. Nevertheless, the third set of spacers 1017-1021 caninclude a first side 1017 a-1021 a that has a dimension that is the sameor different than a second side 1017 b-1021 b. The various sides caninclude any appropriate dimension, however, the dimension of side 1017b-1021 b can be varied for various purposes, such as a reason similar tovarying the dimension of the first spacer sets 1016-1020. The side 1017b-1021 b can include a dimension 1017′-1021′ that can be selected forany appropriate purpose, such as a selected offset, including ananterior or posterior offset. The offsets can be any appropriateoffsets, and can be similar to, different, or complementary to theoffsets of the spacers 1016-1020. Further, the third set of spacers1017-1021 can include a third side 1017 c-1021 c. It will be understoodthat the various sides can be any appropriate portions of the spacers1017-1021 and has described the sides merely for the discussion herein.Nevertheless, the third side, 1017 c-1021 c can also include a variabledimension 1017″-1021″. The dimension 1017″-1021″ can include anyappropriate dimension, such as dimensions similar to the dimensions ofthe second spacer sets 1030-1034.

Therefore the third spacer set 1017-1021 can include a variabledimension of more than one side or portion of the spacers 1017-1021 forvarious purposes. For example, it can be selected to provide the spacers1017-1021 to include a selected offset in more than one direction ororientation relative to the prosthesis 1000 or an anatomy into which itis positioned. Therefore, the spacers 1017-1021 can be used to achievean appropriate orientation of the prosthesis 1000 in a single member.Nevertheless, it will be understood that a modular spacer assembly canbe provided to achieve a selected offset in the prosthesis 1000. Havinga spacer member that is formed as a single portion or body is notnecessary and a modular spacer system can be provided. Nevertheless, asingle spacer can include an offset in various dimensions, as exemplaryillustrated in the spacers 1017-1021.

Further, the spacers 1017-1021 can include a passage 1017 d-1021 dsimilar to the passages described above in the various spacer systems.The passage 1017 d-1021 d can be circular, oblong, slotted, or anyappropriate orientation, size, or the like. The select passage 1017d-1021 d can be provided to interact with the passages 72 and thebearing members 1002 and 1006 to achieve a selected orientation of thespacer members relative to the bearing members 1002 1006.

With reference to FIG. 37 and continuing reference to FIG. 36, thedetailed cross-sectional view of the condylar portions 1004, 1006relative to the second bearing member 18 is illustrated in an assembledmanner. As illustrated in FIG. 37, a selected one of the spacers, suchas the spacer 1030 can be inserted into the slot 68 to displace thesecond condylar portion 1006 relative to the first condylar portion1004. Therefore, the angle 1026 is formed between the first center 1012and the second center 1014 with the condylar portions 1004, 1006.Further, as illustrated in FIG. 37, the second condylar portion 1006 caninclude the dimension 1010 that is larger than the dimension 1008 of thefirst condylar portion 1004. Thus, the condylar portion 1006 can bedesigned to mimic a selected portion of the anatomy, if so selected.

Nevertheless, it is still understood that the bearing surfaces 66 canbear on the bearing member 84 of the second bearing member 18 in anappropriate manner. Thus, the condylar pin 62 does not or is notrequired for proper articulation and may not engage a selected portionof the bearing member 84 after positioning or implantation of theprosthesis 1000. For similar reasons, the pin 62 is not required in theassembly as discussed above. The pin 62 can be omitted for variousreasons, such as ease of assembly. Although one skilled in the art willunderstand that the pin 62 can be used for various reasons, includingstability, strength, alignment, and the like. Also, the selectedanatomical geometry can be obtained with the prosthesis 1000, which canuse any or a plurality of the spacers 1016-1020, 1030-1034, or 1017-1021to achieve any appropriate offset or angle and also the dimension of thecondylar portions 1004, 1006 can be selected to achieve the appropriateresults.

With reference to FIG. 38, a modular prosthesis assembly 1060 caninclude various portions, including those discussed above. It will beunderstood that the similar portions can be referenced by like numeralsand a detailed description thereof need not be necessary here tounderstand the various embodiments. Nevertheless, the first stemassembly 12 can be provided to interconnect with a first bearingassembly 1062 and a second stem assembly 14 and a third stem assembly220. As discussed above, the fourth bearing component 222 can beprovided with the stem assembly 220 to interconnect with the radius toreplace articulating portion thereof. It will be understood that thestem assembly 220 can be provided with various portions to achieve areplacement of a selected portion of the radius.

It will be further understood that, as described above in variousembodiments, that the bearing portion 222 can be formed as a singlemember with the second stem assembly 14 according to variousembodiments. The first bearing assembly 1062 can include a firstcondylar portion 1064, a second condylar portion 1066 and the extension240. The extension 240 can be provided to extend from a selected portionof the first bearing member 1062 such as medial or laterally from thefirst bearing member 1062. The extension 240 can define the extensionbearing member 242 that can articulate with the bearing portion 222 ofthe stem 220 or with the natural portion of the radius. Further, asdiscussed above, the bearing surface 222 can articulate with the naturalportion of the humerus if so selected. Also, the second bearing member18 can be provided in a substantially linked, unlinked or unconstrained,semi-constrained or linked, or a slot that allows access to the bore 86in any appropriate manner.

The first bearing member 1062 can be interconnected with the first stemmember 12 in any appropriate manner, including the various screws orfixing member 64 as described above. Further, the condylar portions1064, 1066 can be interconnected with the condylar pin 62 c in anyappropriate manner, including those discussed above. Nevertheless, thefirst condylar member 1064 can be provided in a different manner,geometry, size, etc., than a second condylar member 1066.

As discussed above, the first condylar member 1064 can have acenterpoint 1068 that can define a center of a sphere or any otherregular or irregular shape. For example, the first condylar portion 1064can define a spherical radius 1070 that extends from the center 1068 toan edge of the condylar member 1064. The second condylar member 1066 canalso define a center 1072, which can be the center of a sphere or anyother appropriate shape or irregular shape. Further, the second condylarportion can define a second spherical radius 1074. As discussed above,the spherical radii 1070, 1074 can be provided to be equal, different,or in any appropriate combination. Nevertheless, it will be understoodthat the condylar portions 1064, 1066 can include a different dimensionand be interconnected with the various portions, such as the extension242 to articulate with various portions of the anatomy or prosthesespositioned therein. It will also be understood that the condylarportions 1064, 1066 can interconnect with the first stem member 12 inany appropriate manner. Therefore, various further portions, such as thespacers 1016-1020, 1030-1034, or 1017-2021 can be provided with theprosthesis system 1060.

It will be understood that the various embodiments of the prostheses,whether linked or unlinked or constrained or unconstrained can beprovided in various portions of the anatomy. Nevertheless, the exemplaryelbow prostheses can be provided in various manners for selection by auser. As discussed above, a kit can include each and every of thevarious portions of the various embodiments for selection by a userduring an operative procedure, prior to an operative procedure, or atany appropriate time. Therefore, the modular prosthesis, according tovarious embodiments, can be provided for use by a user in a selectedmanner to achieve a selected result.

Further, with exemplary reference to FIG. 39, the prosthesis 1000 can bepositioned in the anatomy in any appropriate manner. The modularprosthesis can be provided to be positioned relative to various portionsof the anatomy, such as a humerus, a radius, an ulna, or any appropriateportions through a selected incision 1200 relative to the elbow 1202joint between the hummers 1204 and ulna 1206. It will be understood thatthe modular nature of the prosthesis 1000, can be provided for aprocedure that can be performed through a relatively minor incision thatneed not be larger than various portions of the modular prosthesis. Thiscan achieve various results, such as minimizing recovery time,minimizing operation time, or various selected results. Further, asdiscussed above, the modular nature of the various portions and variousembodiments can provide for achieving a selected revision procedure. Forexample, having the various sizes of the condylar portions, which caninclude different dimensions, a revision procedure can be provided tomaintain or augment a selected result to achieve a more anatomicalresult in a selected period. Further, the prosthesis, according tovarious embodiments, can be changed from a constrained to unconstrainedor from an unconstrained to a constrained. The change can be providedduring a selected procedure, such as a revision procedure to account forchanges in the anatomy over time. Nevertheless, the modular prosthesisaccording to various embodiments can be provided for selection by a userto achieve a more natural anatomical result after implantation of theprosthesis.

While the description in the specification and illustrated in thedrawings are directed to various embodiments, it will be understood thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the teachings andthe appended claims. In addition, many modifications may be made toadapt a particular situation or material to the teachings withoutdeparting from the scope thereof. Therefore, it is intended that theteachings and claims are not be limited to any particular embodimentillustrated in the drawings and described in the specification, but thatthe teachings and claims can include any embodiments falling within theforegoing description and the appended claims.

1. A prosthesis assembly for implanting in a selected portion of theanatomy, comprising: a first condylar bearing member having a firstdimension; a second condylar bearing member having a second dimensiondifferent than the first dimension; a third bearing member operable toarticulate with at least one of the first condylar bearing member or thesecond condylar bearing member.
 2. The prosthesis assembly of claim 1,further comprising: a condylar connecting member to connect the firstcondylar bearing member to the second condylar bearing member.
 3. Theprosthesis assembly of claim 1, further comprising: a humeral stem tointerconnect with at least one of the first condylar member, the secondcondylar member, or combinations thereof.
 4. The prosthesis assembly ofclaim 1, wherein either of said first dimension or the second dimensionis a spherical radius of the respective first condylar bearing member orthe second condylar bearing member.
 5. The prosthesis assembly of claim1, wherein the third bearing member includes a first bearing portionoperable to articulate with the first condylar bearing member and asecond bearing portion to articulate with the second condylar bearingmember.
 6. The prosthesis assembly of claim 1, further comprising: anulna stem member extending from the third bearing member to extend intoa portion of the anatomy.
 7. The prosthesis assembly of claim 1, whereinthe second condylar bearing member includes a plurality of selectablesecond condylar bearing members and each has a different seconddimension and wherein each of the plurality of second dimensions differfrom the first dimension.
 8. The prosthesis assembly of claim 7, whereinthe first condylar bearing member can be interconnected with a selectedone of the second condylar bearing members having a selected seconddimension to articulate with the third bearing member.
 9. The prosthesisassembly of claim 3, wherein the humeral stem includes a leg operable tointerconnect with a slot defined by the first condylar bearing member,the second condylar bearing member, or combinations thereof.
 10. Aprosthesis assembly for implanting into an anatomy, comprising: a firststem member to be positioned in a first portion of the anatomy; a firstcondylar bearing member having a first operative center; a secondcondylar bearing member having a second operative center; and a spacermember to be positioned between the first stem member and at least oneof the first condylar bearing member, the second condylar bearingmember, or combinations thereof to offset the first operative centerfrom the second operative center.
 11. The prosthesis assembly of claim10, wherein the offset includes at least one of an anterior to posterioroffset, a superior to inferior offset, or combinations thereof.
 12. Theprosthesis assembly of claim 10, wherein the first condylar bearingmember and the second condylar bearing member define bearing memberslots operable to interconnect with a portion of the first stem.
 13. Theprosthesis assembly of claim 12, wherein the first stem includes a firstleg and a second leg wherein the first leg is operable to interconnectwith the first condylar slot and the second leg is operable tointerconnect with the second condylar slot.
 14. The prosthesis assemblyof claim 13, wherein the spacer member is operable to be positionedrelative to the first leg in the first condylar slot, the second leg inthe second condylar slots, or combinations thereof; wherein the spacerselects a position of the leg relative to the respective first condylarbearing member, the second condylar bearing member, or combinationsthereof.
 15. The prosthesis assembly of claim 1, wherein said spacermember includes a plurality of spacer members, each having a differentdimension.
 16. The prosthesis assembly of claim 15, wherein thedifferent dimension provides a selected offset of the first condylarbearing member relative to the second condylar bearing member.
 17. Theprosthesis assembly of claim 10, wherein the spacer is operable to bepositioned anteriorly, posteriorly, inferiorly, medially, laterally, orcombinations thereof relative to the first stem member.
 18. A prosthesisassembly for replacing a selected portion of the anatomy, comprising: afirst stem member to be positioned in a humerus; a first condylarbearing member to replace a first portion of the humerus having a firstdimension relative to a first operative center; and a plurality ofsecond condylar bearing members to replace a second portion of thehumerus having a second dimension different than the first dimensionrelative to the second operative center; and a plurality of spacermembers to position between the first stem member and at least one ofthe first condylar bearing member, at least one of the plurality ofsecond condylar bearing members, or combinations thereof to achieve aselected offset between the first operative center and the secondoperative center.
 19. The prosthesis assembly of claim 18, furthercomprising: a condylar connecting member to interconnect the firstcondylar bearing member and a selected one of the plurality of secondcondylar bearing members.
 20. The prosthesis assembly of claim 19,further comprising: a third bearing member to articulate only with thefirst condylar bearing member, the selected of the plurality of thesecond condylar bearing members, or combinations thereof.
 21. Theprosthesis assembly of claim 20, wherein the third bearing memberextends from a second stem member to be positioned in the radiusrelative to the humerus.
 22. The prosthesis assembly of claim 18,wherein the first condylar bearing member defines a first slot, each ofthe plurality of the second condylar bearing members define a secondcondylar slot, wherein the first stem member includes a portion operableto extend into the at least one of the first condylar slot, the secondcondylar slot, or combinations thereof.
 23. The prosthesis assembly ofclaim 22, wherein at least one of the plurality of spacer members ispositioned in at least one of the first condylar slots, the secondcondylar slot, or combinations thereof.
 24. The prosthesis assembly ofclaim 18, wherein the plurality of spacer members are positionedrelative to the first condylar bearing member and at least one of theplurality of second condylar bearing members to obtain a selected offsetthat is at least one of an anterior to posterior offset, a superior toinferior offset, a medial to lateral offset, or combinations thereof.